TW202414111A - Method for electron beam-induced processing of a defect of a microlithographic photomask - Google Patents

Abstract

Method for electron beam-induced processing of a defect (D) of a microlithographic photomask (100), including the steps of: (a) providing (S1) an activating electron beam (202) at a first acceleration voltage (EHT1) and a process gas in the region (112) of a defect (D) of the photomask (100) for the purpose of repairing the defect (D), and (b) producing (S2) at least one image (110) of the photomask (100), in which the region (112) of the defect (D) is captured at least in part, by providing an electron beam (202) at at least one second acceleration voltage (EHT2, EHT3, EHT4) which differs from the first acceleration voltage (EHT1), for the purpose of determining a quality of the repaired defect (D).

Description

Method for electron beam induction treatment of defects in lithography masks

The present invention relates to a method for electron beam induction treatment of a defect in a lithography mask.

The content of the priority application DE 10 2022 118 874.4 is incorporated herein by reference in its entirety.

Lithography is used to produce microstructured parts, such as integrated circuits. Lithography is performed using a lithography apparatus having an illumination system and a projection system. Here, an image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, which is coated with a photosensitive layer (photoresist) and is arranged on the image plane of the projection system, in order to transfer the mask structure to the photosensitive coating of the substrate.

Driven by the need for smaller structures in integrated circuit production, EUV lithography equipment is being developed using wavelengths ranging from 0.1nm to 30nm, particularly light at a wavelength of 13.5nm.

In this case, the structure size of the lithography mask or the mask itself ranges from a few nm to hundreds of nm. The production of such masks is very complex and costly. This is the case, in particular, because the mask must be defect-free to ensure that the structures produced on the silicon wafer using the mask exhibit the desired functionality. In particular, the quality of the structures on the mask determines the quality of the integrated circuits produced on the wafer using the mask.

It is for this reason that lithography masks need to be inspected for defects and repaired if found. Typical defects include the absence of the intended structure, e.g. due to an unsuccessful etching process, and the presence of non-ideal structures, e.g. due to the etching process being carried out too quickly or affecting the process at the wrong location. These defects can be remedied by targeted etching of excess material or targeted deposition of additional material at the right location; this can be achieved, for example, in a very targeted manner by means of electron beam induction processing (FEBIP, "focused electron beam induction processing").

DE 10 2017 208 114 A1 describes a method for particle beam induced etching of a lithography mask. In this case, a particle beam (in particular an electron beam) and an etching gas are provided at the locations to be etched on the lithography mask. The particle beam activates a local chemical reaction between the material of the lithography mask and the etching gas, resulting in localized ablation of the material of the lithography mask.

Against this background, an object of the present invention is to provide an improved method for electron beam induction processing of a defect in a lithography mask.

Therefore, a method for electron beam induced treatment of a defect in a lithography mask is proposed, comprising the following steps: a) providing an activating electron beam at a first accelerating voltage and a treatment gas in the region of the defect in the mask to repair the defect, and b) in order to determine the quality of the repaired defect, generating at least one image (110) of the mask by providing an electron beam (202) at at least one second accelerating voltage different from the first accelerating voltage, wherein the region of the defect is at least partially captured.

For example, at least one image of the reticle generated in step b) is generated based on the interaction of the electrons of the electron beam with the material of the reticle. The energy of the electrons of the electron beam depends on the accelerating voltage provided to the electron beam (primary beam). The greater the accelerating voltage, the higher the energy of the electrons. The higher the energy of the electrons, the greater the penetration depth into the reticle material and the greater the interaction volume of the electrons interacting with the reticle material. In other words, changing the accelerating voltage allows recording images of the reticle from different depth layers in the reticle.

By providing the electron beam with at least one second accelerating voltage to generate at least one image of the reticle, information useful for determining the quality of the repaired defect can be obtained from a depth different from the depth allowed by the first accelerating voltage.

The interaction between the electrons of the electron beam (primary beam) and the mask material includes, for example, the interaction between the electrons of the primary beam and the atoms of the object to be inspected, and the generation of secondary electrons. In addition, the interaction may also include, for example, backscattered electrons.

For example, an electron beam is scanned over a reticle and/or a portion of a reticle.

If in step b) a plurality of images of the reticle are generated, in which at least parts of the defect area are captured, then the plurality of images are generated in particular in such a way that they capture and/or represent the same area of the reticle.

If multiple images of the mask are generated in step b), this means that each of the multiple images is generated using an electron beam provided at a corresponding second accelerating voltage. Specifically, the multiple second accelerating voltages used to generate the multiple images are different from each other (i.e., different in pairs) and are also different from the first accelerating voltage.

For example, at least one image of the mask is recorded using a scanning electron microscope (SEM). For example, the at least one image of the mask has a spatial resolution on the order of a few nm.

For example, the method may include the step of determining the quality of the repaired defect.

The defect repair in step a) comprises, for example, etching of the defect, locally ablating material from the mask within the scope of the etching, or depositing material on the mask in the defect area.

By means of the proposed method, redundant structures in the defect region can be better etched away during post-processing of the mask after step b), i.e., for example, by re-performing step a), or missing structures in the defect region can be better enhanced. Specifically, the proposed method allows better and more accurate etching away of the edge region of the defect, or missing structures in the edge region of the defect can be better and more accurately enhanced.

For example, a lithography mask is a mask used in an EUV lithography system. In this case, EUV stands for "extreme ultraviolet" and refers to the wavelength range of the working light between 0.1nm and 30nm, in particular 13.5nm. Within the EUV lithography system, beam shaping and illumination systems are used to direct the EUV radiation onto a mask (also called a "reticle"), which in particular takes the form of a reflective optical element (reflective mask). The mask has a structure that is imaged in a reduced form onto a wafer, etc., using the projection system of the EUV lithography system.

For example, a lithography mask can also be a mask for a DUV lithography system. In this case, DUV stands for "deep ultraviolet" and refers to an operating wavelength range between 30 nm and 250 nm, in particular 193 nm or 248 nm. In a DUV lithography system, beam shaping and illumination systems are used to direct the DUV radiation onto the mask, in particular in the form of transmission optics (transmission mask). The mask has a structure that is imaged in a reduced form onto a wafer or the like using the projection system of the DUV lithography system.

For example, a lithography mask comprises a substrate and a structure formed on the substrate by means of a coating. For example, the mask is a transmissive mask, in which case the pattern to be imaged is realized in the form of an absorbing (i.e., opaque or partially opaque) coating on a transparent substrate. Alternatively, the mask can also be a reflective mask, for example, especially for EUV lithography. The mask can also be used for nanoimprint lithography (NIL).

By way of example, the substrate comprises silicon dioxide (SiO ₂ ), such as fused silica. By way of example, the structured coating comprises chromium, chromium compounds, tantalum compounds and/or compounds made of silicon, nitrogen, oxygen, molybdenum and/or ruthenium. The substrate and/or the coating may also contain other materials.

In the case of a mask for EUV lithography equipment, the substrate may include an alternating sequence of molybdenum and silicon layers.

Using the proposed method, defects of a photomask, in particular defects of a structured coating of the photomask, can be repaired. In particular, the defects are caused by incorrectly applying a coating of the photomask, such as an absorbing coating or a reflective coating, to a substrate. This method can be used to enhance locations on the photomask where the coating is absent. Furthermore, this method can be used to remove the coating from locations on the photomask where the coating was incorrectly applied.

Quality inspection of repaired defects, especially the quality of the repaired defects. Quality inspection of repaired defects, especially defect parameters. Quality inspection of repaired defects, for example, the degree of correspondence between the repaired defects and the predetermined configuration of the mask, a greater degree of correspondence means a higher quality of the repaired defects. Quality inspection of repaired defects of the structured coating of the mask, for example, the degree of correspondence between the repaired defects of the structured coating and the predetermined configuration of the structured coating.

Determining the quality of the repaired defect includes, for example, determining a deviation and/or a degree of deviation of the parameter from at least one image generated from the reticle based on reference parameters determined from the reference data.

For example, in step a), an image of at least a portion of the mask can be provided and/or generated, in which the defect is captured, in particular the defect is completely captured. For example, the geometric shape of the defect in the image can be determined as the repair shape in step a). For example, the two-dimensional geometric shape of the defect is determined. The determined geometric shape of the defect is referred to as the so-called repair shape in the following. For example, the repair shape contains n pixels. In step a), an electron beam is generated with a first accelerating voltage and, for example, the electron beam is guided to each of the n pixels of the repair shape.

For example, the process gas is a precursor gas and/or an etching gas. For example, the process gas can be a mixture of multiple gas components, i.e., a process gas mixture. For example, the process gas can be a mixture of multiple gas components, wherein each gas component has only a specific molecular type.

In particular, alkyl compounds of main group elements, metals or transition elements can be considered as suitable precursor gases for the deposition or growth of protrusion structures. Examples include cyclopentadienyl (trimethyl) platinum ( _CpPtMe3Me = _CH4 ), methylcyclopentadienyl (trimethyl) platinum (MeCpPtMe3), tetramethyltin ( _SnMe4 ), trimethylgallium ( _GaMe3 ), ferrocene ( _Cp2Fe ), chromium diaryls ( _Ar2Cr ) and/or _carbonyl compounds of main group elements, metals or transition elements, such as chromium hexacarbonyl (Cr(CO) ₆ ), molybdenum hexacarbonyl (Mo(CO) ₆ ), tungsten hexacarbonyl (W(CO) ₆ ), dicobalt octacarbonyl ( _Co2 (CO) ₈ ), triruthenium dodecacarbonyl ( _Ru3 (CO) ₁₂ ), iron pentacarbonyl (Fe(CO) ₅ ), and/or alkoxide compounds of main group elements, metals or transition elements, for example, tetraethoxysilane (Si(OC ₂ H ₅ ) ₄ ), tetraisopropoxytitanium (Ti(OC ₃ H ₇ ) ₄ ) and/or halides of main group elements, metals or transition elements, for example, tungsten hexafluoride (WF ₆ ), tungsten hexachloride (WCl ₆ ), titanium tetrachloride (TiCl ₄ ), boron trifluoride (BCl ₃ ), silicon tetrachloride (SiCl ₄ ) and/or complexes with main group elements, metals or transition elements, for example, bis(hexafluoroacetylacetonate)copper (Cu(C ₅ F ₆ HO ₂ ) ₂ ), trifluoroacetylacetonate dimethylgold (Me ₂ Au(C ₅ F ₃ H ₄ O ₂ )) and/or organic compounds such as carbon monoxide (CO), carbon dioxide (CO ₂ ), aliphatic and/or aromatic hydrocarbons, and more of the same.

For example, the etching gas may include: xenon difluoride ( _XeF2 ), xenon dichloride ( _XeCl2 ), xenon tetrachloride ( _XeCl4 ), steam ( _H2O ), heavy water ( _D2O ), oxygen ( _O2 ), ozone ( _O3 ), ammonia ( _NH3 ), nitrosyl chloride (NOCl) and/or one of the following halogenide compounds: XNO, _XONO2 , _X2O , _XO2 , _X2O2 , _X2O4 , _X2O6 , where X is a _{halide .} Other etching gases used to etch one or more deposition test structures are described in detail in applicant's U.S. patent application ₍ serial number 13/0103281).

The process gas may include additional gases, such as _oxidizing gases, such as hydrogen peroxide ( _H2O2 ), nitrous oxide ( _N2O ), nitrogen oxides (NO), nitrogen dioxide ( _NO2 ), nitric acid ( _HNO3 ) and other oxygen-containing gases and/or halides, such as chlorine ( _Cl2 ), hydrogen chloride (HCl), hydrogen fluoride (HF), iodine ( _I2 ), hydrogen iodide (HI), bromine ( _Br2 ), hydrogen bromide (HBr), phosphorus trichloride ( _PCl3 ), phosphorus pentachloride ( _PCl5 ), phosphorus trifluoride ( _PF3 ) and other halogen-containing gases and/or reducing gases, such as hydrogen ( _H2 ), ammonia ( _NH3 ), methane ( _CH4 ) and other hydrogen-containing gases. These additional gases may be used, for example, in etching processes, as buffer gases, as passivation media, etc.

For example, a starting electron beam is provided by a device, which may include: an electron source for generating an electron beam under a varying acceleration voltage; an electron beam guiding device (e.g., a scanning unit) configured to guide the electron beam to each pixel of the repair shape of the mask; an electron beam shaping device (e.g., an electron or electron beam optical element) configured to shape the electron beam, in particular to focus the electron beam; at least one storage container configured to store a processing gas or at least one gaseous component of the processing gas; at least one gas supply device configured to provide the processing gas or at least one gaseous component of the processing gas to the corresponding pixel of the repair shape at a predetermined gas flow rate; and at least one detector for detecting secondary electrons and/or backscattered electrons.

For example, in step a) of the method a modified scanning electron microscope is used to provide the electron beam.

In step a), the activating electron beam activates in particular a local chemical reaction between the photomask material and the process gas, which results in a local deposition of material from the gas phase on the photomask or in a transformation of the material into the gas phase.

In step a), an activating electron beam is continuously provided at each pixel of the repaired shape, for example, using an electron beam guiding device. The activating electron beam retains a predetermined dwell time at each pixel so as to induce a chemical reaction between the processing gas and the mask material at the location of the corresponding pixel. For example, the dwell time is 100 ns. However, other values of dwell time may also be used. For example, the dwell time of the activating particle beam at each pixel of the repaired shape is less than or equal to 500ns, less than or equal to 400ns, less than or equal to 300ns, less than or equal to 200ns, less than or equal to 100ns and/or less than or equal to 50ns.

For example, at least one image of the reticle in step b) of the method is recorded using the same improved scanning electron microscope used to provide the activating electron beam in step a) of the method. For example, at least one image of the reticle in step b) of the method is recorded using the same improved scanning electron microscope used to record an image of at least a portion of the reticle to determine the repaired shape of the defect in step a).

In step b), an electron beam is guided (scanned) on the mask or a portion of the mask, for example using an electron beam guiding device. The electrons of the electron beam (primary beam) interact with the material of the mask and, for example, generate secondary electrons and/or backscattered electrons, which are detected using at least one detector. At least one image of the mask is generated based on the captured secondary electrons and/or backscattered electrons.

According to one embodiment, at least one second accelerating voltage is greater than the first accelerating voltage.

The depth of the mask is caused to be greater than the possible depth obtained by applying the first accelerating voltage, and when at least one image is generated in step b), an image used in the restoration process in step b) can be captured.

For example, the first accelerating voltage and the second accelerating voltage are both within the range of greater than or equal to 0.2 kV, 0.4 kV and/or 0.6 kV. For example, the first accelerating voltage and the second accelerating voltage are each within the range of less than or equal to 2 kV, 4 kV, 6 kV, 8 kV and/or 10 kV. For example, the first accelerating voltage and the second accelerating voltage are each within the range of 0.6 kV to 2 kV or 0.2 kV to 10 kV.

In addition, for example, the first accelerating voltage is in a range of less than 1 kV, and the second accelerating voltage is in a range of more than 1 kV.

According to another embodiment, in order to obtain depth information related to the structure of the mask, multiple images of the mask are generated using an electron beam under corresponding multiple second accelerating voltages, where the second accelerating voltages are different from the first accelerating voltage and the second accelerating voltages are also different from each other.

In particular, the same image portion of the reticle is captured in a plurality of images of the reticle. In particular, depth information of the structure of the reticle is acquired in a direction perpendicular to a main extension plane of the reticle.

For example, the structure of the mask is the structured coating of the mask.

According to another embodiment, step b) is performed on-site relative to step a).

As a result, the quality of the repaired defects of the photomask can be checked on site immediately after the repair in step a). Specifically, it can be immediately determined whether the quality of the repair meets the known quality level (e.g., whether the degree of deviation of the repaired defects from the reference data is less than a predetermined threshold). For example, the photomask can only be output (e.g., discharged) from the processing equipment (e.g., scanning electron microscope equipment) if the determined quality meets the standard.

In particular, the photomask remains in the same position during steps a) and b). For example, the photomask also remains in the same position and orientation during steps a) and b). For example, the photomask is placed on a sample stage for performing step a), and the photomask also remains on the sample stage during step b).

According to another embodiment, steps a) and b) are performed in a vacuum environment, and the photomask is kept in the vacuum environment between steps a) and b).

Therefore, the photomask can be discharged from the vacuum environment according to the quality determined in step b).

According to another embodiment, steps a) and b) are performed using the same scanning electron microscope device, and/or the electron beam (202) at the first accelerating voltage and the electron beam at the at least one second accelerating voltage are generated by the same electron source.

For example, the electron source comprises a cathode for releasing electrons and an anode for accelerating the released electrons in the direction of the anode. For example, according to an accelerating voltage applied between the cathode and the anode, the electrons are accelerated from the cathode to the anode in the direction of the anode. For example, the electron source comprises an adjusting device for adjusting the accelerating voltage applied between the cathode and the anode. For example, the anode has a channel opening so as to provide the accelerated electrons as an electron beam.

According to another embodiment, the method comprises the following steps: An image analysis using the at least one image generated by the mask and/or a comparison based on the at least one image generated by the mask and reference data for the at least one second accelerating voltage to determine the quality of the repaired defect.

The reference data for at least one second accelerating voltage particularly comprises reference data for each of the at least one second accelerating voltage. In other words, separate reference data is provided and/or generated for each of the at least one second accelerating voltage.

In particular, image analysis includes computer-assisted image analysis.

According to another embodiment, the method comprises the steps of: generating the reference data using a simulation based on a known model of the reticle, wherein during the simulation, at least one reference image is generated based on a simulated interaction between the electron beam and the known model of the reticle, the electron beam corresponding to the at least one second accelerating voltage.

Specifically, the known model of the reticle corresponds to a defect-free reticle and/or a target configuration of the reticle. For example, the known model of the reticle includes a digital model of the reticle, such as a CAD model of the reticle.

According to another embodiment, a region outside the defect is captured in the at least one image generated of the mask, and the method comprises the following steps: Generating the reference data based on an image analysis of the region outside the defect.

The area outside the defect is in particular a defect-free and/or unrepaired area of the mask. The area outside the defect is in particular a defect-free area before step a).

In an embodiment, the deviation and/or degree of deviation of the parameter and/or measurable property is determined based on at least one generated image of the mask, and during the determination of the quality of the repaired defect, the determination is made based on a measurable reference characteristic of a reference parameter or reference data. For example, the deviation and/or degree of deviation is determined for each of the at least one second accelerating voltage.

The parameter determined from the at least one generated image of the reticle and/or the measurable characteristic determined therefrom is, for example, a parameter/measurable characteristic of the outline of a structure in the at least one generated image of the reticle, a size of a structure in the at least one generated image of the reticle and/or an intensity profile of the at least one generated image of the reticle. For example, the reference parameter and/or the measurable reference characteristic is a parameter/measurable characteristic of a reference outline determined based on reference data, reference size and/or reference intensity profile.

According to another embodiment, the determination (S4) of the quality of the repaired defect (D) includes: Determining a contour of one or more structures in the at least one image generated by the mask, and/or Determining a size of the one or more structures based on the determined contour.

The contours of the one or more structures include, for example, edges and/or contours of the one or more structures of the mask. Determining the contours of the one or more structures of the mask includes, for example, fitting a mathematical function, such as a linear function (e.g., a straight line), the one or more structures of the mask and/or portions of the one or more structures of the mask in at least one generated image.

Blurred edges and/or boundaries of (e.g., very small) structures may also be captured by determining the outline of one or more structures of the reticle in at least one generated image. Blurred edges and/or boundaries may occur due to the very small imaged structures and the limited spatial resolution of the generated images. By determining the outline, the size of the one or more structures may be more accurately measured.

The dimensions of one or more structures include, for example, the size (eg, width or length) of the corresponding structure or the spacing between multiple structures.

According to another embodiment, during the determination of the quality of the repaired defect, a deviation of the determined profile from a reference profile in the reference data is determined, and/or a deviation of the determined size from a reference size in the reference data is determined, in particular for each of the at least one second accelerating voltage.

For example, the reference data includes a reference image. For example, the reference image is based on a pure simulation. The reference image can also be based on an electron beam application of a reference mask or a reference region of a mask to be repaired or a repaired mask. The reference image can be, for example, a SEM image of a reference mask or a reference region of a mask to be repaired or a repaired mask.

According to another embodiment, during the determination of the quality of the repaired defect, an intensity distribution of the at least one image produced of the mask is determined, and a deviation of the determined intensity distribution from a reference intensity distribution of reference data (R) is determined, in particular for each of the at least one second accelerating voltage.

For example, the intensity distribution is a one-dimensional intensity distribution that reproduces the intensity of the corresponding image along a line in the image. In other examples, the intensity distribution can also be a two-dimensional intensity distribution.

According to another embodiment, the deviation of the determined intensity distribution from the reference intensity distribution is determined for a region of the generated image that includes an outline of one or more structures of the mask.

As a result, changes in the intensity distribution at the contours (e.g. boundaries and/or edges) of one or more structures can be detected.

According to another embodiment, the intensity distribution determined is a one-dimensional or two-dimensional intensity distribution.

According to another embodiment, during the determination of the quality of the repaired defect, the degree of deviation between a parameter determined based on the at least one image generated by the mask and a reference parameter determined based on the reference data is determined. The method comprises the following steps: Determining whether the determined deviation is less than a predetermined threshold, and/or If the determined deviation is less than the predetermined threshold, controlling an HMI unit to output a communication: "satisfactory", and/or controlling a mask output unit to output the repaired mask, and/or If the determined deviation is greater than or equal to the predetermined threshold, controlling the HMI unit (242) to output a communication: "unsatisfactory".

Therefore, the quality level of the repair of the reticle can be determined based on the determined deviation relative to the reference data.

Outputting the repaired mask using the mask output unit includes, for example, outputting the mask from a processing device (e.g., a scanning electron microscope device), wherein steps a) and b) are performed. Outputting the repaired mask includes, for example, outputting and/or exhausting the mask from a vacuum environment and/or a vacuum enclosure, wherein steps a) and b) are performed.

Therefore, if the determined quality level of the reticle repair is sufficient and/or satisfactory relative to the predetermined specifications, the repaired reticle can only be exported from the processing equipment (e.g., scanning electron microscope equipment), vacuum environment and/or vacuum enclosure. However, if the determined quality level is not up to standard and/or satisfactory relative to the predetermined specifications, the reticle is retained in the processing equipment (e.g., scanning electron microscope equipment), vacuum environment and/or vacuum enclosure. The reticle can then be further inspected and/or processed there.

Specifically, an HMI unit is a human-machine interface unit. For example, an HMI unit includes a display device, such as a display of a computer, laptop, tablet and/or smartphone, for outputting communications in the form of text or images. In addition or as an alternative, the HMI unit may also include a speaker for outputting voice communications, for example.

In the present case, "one" or "an" is not necessarily to be understood as being limited to one element. Instead, multiple elements may be provided, for example two, three or more. Any other numerals used herein should not be understood as limiting the exact number of elements. On the contrary, unless otherwise specified, there may also be deviations of increasing and decreasing values.

Further possible implementations of the present invention also include combinations not explicitly mentioned in the context relative to the features or embodiments described in the exemplary embodiments. In this case, those skilled in the art will also add various aspects as improvements or supplements to the corresponding basic forms of the present invention.

Unless otherwise specified, identical or functionally identical components have the same reference numerals in the accompanying drawings. It should also be noted that the drawings in the accompanying drawings are not necessarily drawn to scale.

1 schematically shows a plan view of details of a lithography mask 100. In the example shown, the mask 100 is a transmission lithography mask 100. The mask 100 includes a substrate 102. The substrate 102 is optically transparent, especially at the wavelength to which the mask 100 is exposed. For example, the material of the substrate 102 includes fused silica.

A structured coating 104 (pattern element 104) has been applied to a substrate 102. In the example shown, the coating 104 is provided on the substrate 102 in periodic strips 106, 106'. In other words, the mask 100 has a periodic structure 106, 106'. The mask 100 is used, for example, to produce a diffraction grating (grating) by photolithography. The coating pattern of the mask 100 can also differ from the coating pattern shown and/or can be used to produce different components.

Specifically, the coating 104 is a coating made of an absorbing material. For example, the material of the coating 104 includes a chromium layer. For example, the thickness of the coating 104 ranges from 50 nm to 100 nm. The structural sizes B1 and B2 of the structure 106 formed by the coating 104 on the substrate 102 of the mask 100 are, for example, 20 to 200 nm. The structural sizes B1 and B2 can also be greater than 200 nm, for example, in the micrometer range. The structural sizes B1 and B2 can also be different at different positions of the mask 100.

In other examples, other materials and other layer thicknesses mentioned (eg, thinner layer thicknesses, such as “thin EUV mask absorber”) may also be used for the substrate 102 and the coating 104 .

Instead of the transmissive light mask 100 shown in FIG. 1 , the light mask 100 may also be a reflective light mask.

Sometimes, defects D may occur during the production of the mask, for example because the etching process did not work completely as expected. In FIG. 1 , such defects D are indicated by hatching. This is excess material, because in the template of the mask 100, the coating 104 is not removed from this area even if two coating areas 104 that are adjacent to each other are conceived as separated. It can also be said that the defects D form a network. In this case, the size of the defect D corresponds to the structure size B2. Other defects that are smaller than the structure size B2 (for example, of the order of 5 to 20 nm) are also known. In order to ensure that the structure produced in the lithography equipment using the mask 100 has the desired shape on the wafer and that the (semiconductor) component produced in this way therefore realizes the desired function, it is necessary to repair defects such as the defect D shown in FIG. 1 or other defects. In this example, the web needs to be removed in a targeted manner, for example by particle beam induced etching.

Fig. 2 shows a cross-sectional view of the photomask 100 along the line II-II in Fig. 1. The coating layer 104 depicted with hatching is defective and indicates a defect D to be repaired.

FIG3 shows an apparatus 200 for electron beam induced processing of defects in a lithography mask, such as defect D of the mask 100 of FIG1 and FIG2. FIG3 schematically shows a cross section of several components of the apparatus 200, which can be used for electron beam induced repair (in this case, etching) of the defect D in the mask 100. In addition, the apparatus 200 can also be used to image the mask, in particular the structured coating 104 of the mask 100, and the defect D before, during, and after the repair process is performed.

The device 200 shown in FIG3 represents a modified scanning electron microscope 200 . In this case, an electron beam 202 is used to repair the defect D. Using the electron beam 202 as the activating particle beam has the following advantages: the electron beam 202 does not substantially damage the mask 100 , or only causes slight damage, in particular the substrate 102 of the mask 100 .

In an embodiment, in addition to the electron beam 202, a laser beam (not shown in FIG. 3) may also be used for the local repair process of the activation mask 100.

The device 200 is mainly disposed in a vacuum housing 204. A vacuum pump 206 is used to maintain a certain pressure (vacuum environment 244) in the space surrounded by the vacuum housing 204.

For example, the apparatus 200 is a repair apparatus (repair tool) for a lithography apparatus, such as a mask for a DUV or EUV lithography apparatus.

The reticle 100 to be processed is placed on a sample stage 208. The position of the reticle 100 is set, for example, with a precision of a few nm in three orthogonal spatial directions and, for example, additionally on three orthogonal rotational axes using the sample stage 208.

The device 200 includes an electron column 210. The electron column 210 includes an electron source 212 for providing an electron beam 202. For example, the electron source 212 has a cathode 214 for releasing electrons and an anode 216 for accelerating the released electrons in the direction of the anode 216. An accelerating voltage is applied at a voltage source 218 between the cathode 214 and the anode 216. In addition, the anode 216 has, for example, a channel opening 220 in order to provide the accelerated electrons as the electron beam 202. By adjusting the accelerating voltage at the voltage source 218, the energy of the electrons of the electron beam 202 generated by the electron source 212 can be adjusted.

The electron column 210 further includes an electron or beam optical element 222. The electron source 212 generates the electron beam 202, and the electron or beam optical element 222 focuses the electron beam 202 and directs the electron beam 202 to the reticle 100 at the output of the column 210. The electron column 210 further includes a deflection unit 224 (scanning unit 224) configured to direct (scan) the electron beam 202 over the surface of the reticle 100. Instead of the deflection unit 224 (scanning unit 224) provided inside the column 210, a deflection unit (scanning unit) (not shown) provided outside the column 210 may also be used.

The device 200 also includes a detector 226 for detecting secondary electrons and/or backscattered electrons generated by the incident electron beam 202 in the material of the mask 100. For example, as shown, the detector 226 is arranged in a ring around the electron beam 202 in the electron column 210. As an alternative to the detector 226 and/or in addition to the detector 226, the device 200 may also include other/additional detectors (not shown in FIG. 3 ) for detecting secondary electrons and/or backscattered electrons.

The apparatus 200 further includes a gas supply unit 228 for supplying a processing gas to the surface of the photomask 100. For example, the gas supply unit 228 includes a valve 230 and a gas line 232. The electron beam 230 is guided to a position on the surface of the photomask 100 using the electron column 210, and the electron beam 230 can be combined with a processing gas supplied from the outside via the valve of the gas supply unit 228 to perform electron beam induction processing (EBIP) 222 and the gas line 232. In particular, the processing includes deposition and/or etching of a material.

The device 200 further includes a computer device 234, such as a computer, which has a control device 236, a generation device 238, a determination device 240, and an output device 242. In the example of FIG.

The computer device 234, in particular the control device 236, is used to control the device 200. For example, the control device 236 controls the supply of the electron beam 202 by controlling the electron column 210. In this process, the control device 236 is particularly used to control the setting of the acceleration voltage of the voltage source 218, and thus control the energy of the primary electron beam 202. In addition, the control device 236 controls the guidance of the electron beam 202 on the surface of the mask 100 by driving the scanning unit 224. In addition, the computer device 234 controls the supply of the process gas by controlling the gas supply unit 228.

Furthermore, the computer device 234, in particular the generating device 238, receives the measurement data from the detector 226 and/or other detectors of the device 200 and generates the images 108, 110 (FIGS. 1 and 4) from the measurement data, which can be displayed on a monitor (not shown). Furthermore, the images 108, 110 generated from the measurement data can be stored in a storage unit (not shown) of the computer device 234. For example, the spatial resolution of the generated images 108, 110 is of the order of a few nm.

In order to prepare for the repair of the reticle 100, the apparatus 200 (particularly the computer apparatus 234 and/or the generating device 238) is particularly configured to generate at least one image 108 of at least a portion of the reticle 100 based on measurement data of the detector 226 and/or other detectors of the apparatus 200. FIG. 1 shows the image 108 generated based on measurement data obtained before the defect D is repaired.

In order to inspect the repaired mask 100, in particular the structured coating 104 of the mask 100, the device 200 (in particular the computer device 234 and/or the generating device 238) is particularly configured to generate at least one image 110 of at least a portion of the mask 100 based on the measurement data of the detector 226 and/or other detectors. FIG4 shows the image 110 generated based on the measurement data obtained after the defect D is repaired.

The computer device 234, in particular the determination device 240, is configured to identify the defect D (FIG. 1) in the image 108 generated before the repair, locate the defect and determine the geometric shape 112 (repair shape 112) of the defect D. The determined geometric shape 112 of the defect D, i.e., the repair shape 112, is, for example, a two-dimensional geometric shape.

The computer device 234, in particular the determination device 240, is also configured to determine the quality of the repaired defect D in the image 110 generated after the defect D is repaired.

A method for electron beam induction treatment of a defect of a lithography mask (eg, defect D of the mask 100 shown in FIGS. 1 and 2 ) is described below with reference to FIGS. 4 to 11 .

In the first step S1 of the method, an activation electron beam 202 at a first acceleration voltage EHT1 and a processing gas are provided in the region 112 of the defect D of the reticle 100 for repairing the defect D.

For example, the apparatus 200 shown in FIG. 3 is used to repair a defect D of a structured coating 104 of a photomask 100 (FIGS. 1 and 2). To this end, an image 108 of at least a portion of the photomask 100 is recorded, the geometric shape of the defect D is determined in the image 108 as a repair shape 112, and the repair shape 112 is divided into a plurality of pixels. Subsequently, the photomask 100 is scanned in the region 112 of the defect D using an electron beam 202 while providing a processing gas, thereby processing and correcting the defect D having a geometric shape of the repair shape 112. In this case, the activated electron beam 202 is continuously guided to each pixel of the repair shape 112. The electron beam 202 stays at each pixel of the repair shape 112 for a predetermined dwell time. In this case, a chemical reaction of a treatment gas is activated at each pixel of the repaired shape 112 by the electron beam 202. For example, the treatment gas includes an etching gas. For example, the chemical reaction results in the production of volatile reaction products with the material of the defect D to be etched, which are at least partially gaseous at room temperature and can be pumped away using a pump system (not shown). For example, the mask 100 is scanned in the area 112 of the defect D corresponding to the pixel of the repaired shape 112 over a plurality of repetition cycles. In order to (completely) remove the coating 104 in the area of the defect D (FIGS. 1 and 2), for example, one hundred, one thousand, ten thousand, one hundred thousand or one million repetition cycles are required at each pixel of the repaired shape 112.

4 and 5 show the repair results of the photomask 100 shown in FIG1 and FIG2. In this case, FIG4 shows a plan view of the repaired photomask 100, and FIG5 shows a cross-sectional view of the repaired photomask 100 along the V-V line in FIG4.

The coating 104 in the area of the defect D is removed by repair (shown as hatching in FIGS. 1 and 2 ). However, during such repair, it is possible that not only the defect D itself is removed, but also additional structures 106 to the coating 104 of the mask 100 are undesirably modified. For example, FIG. 5 shows that during the repair of the defect D, a portion of the sidewall 114 of the coating structure 106 is also modified. FIG. 5 shows damage to the sidewall 114 in the form of a depression 116 and a protrusion 118 (e.g., a protruding foot 118 that is not properly retained). For example, further defective repair of the defect D and/or defective modification of the desired structure 106 of the reticle 100, which is not shown in FIG. 5 or is shown only using dashed lines, may also include erroneous retention of residual material 120 in the base of the defect D. In addition, for example, incorrect fillets 122 or undercuts 124 of the desired structure 106 may also occur. Although not shown in FIG. 5 , damage to the sidewall 114 of the desired structure 106 may also be in the form of the sidewall 114 having an undesired tilt (i.e., deviating from the vertical direction in FIG. 5 ).

Such undesirable modifications to the structure 106 of the reticle 100 during the repair of the defect D may result in the repaired reticle 100 failing to meet the specified quality requirements. It is advantageous to inspect the repaired reticle 100 for such undesirable modifications to the structure 106. For this purpose, it is particularly advantageous if the reticle 100 remains in the apparatus 200 ( FIG. 3 ), for example, within the vacuum housing 204 of the apparatus 200 and/or on the sample stage 208.

In the second step of the method, at least one image 110 ( FIG. 4 ) of the mask 100 is generated by scanning with the electron beam 202, the image at least partially capturing the area 112 ( FIG. 1 ) of the defect D, in order to determine the quality D of the repaired defect. To this end, the accelerating voltages EHT1 to EHT4 of the voltage source 218 ( FIG. 3 ) are appropriately set, and thus the energy of the electrons in the electron beam 202 is appropriately set.

FIG. 6 illustrates the interaction of electrons of the electron beam 202 with the material of the reticle 100. The greater the accelerating voltage EHT1 to EHT4, and thus the greater the energy of the electron beam 202, the greater the penetration depth T of the electron beam 202 into the material of the reticle 100. Furthermore, the size of the interaction volume 128-134, in which the electrons of the electron beam 202 interact with the material of the reticle 100, also increases with increasing accelerating voltages EHT1 to EHT4. As an example, FIG. 6 illustrates four different accelerating voltages EHT1, EHT2, EHT3, and EHT4 for providing the electron beam 202. In this case, the following applies: EHT4 is greater than EHT3, EHT3 is greater than EHT2, and EHT2 is greater than EHT1. 6, the penetration depths T1, T2, T3, and T4 of each electron beam 202 into the material of the mask 100 increase with increasing accelerating voltages EHT1, EHT2, EHT3, and EHT4. In addition, the sizes of the interaction volumes 128, 130, 132, and 134 also increase with increasing accelerating voltages EHT1, EHT2, EHT3, and EHT4.

For example, in step S1, an activating electron beam 202 is provided with a first accelerating voltage EHT1.

For example, in step S2, at least one image 110 of the mask 100 is generated using the electron beam 202 at at least one second accelerating voltage EHT2, EHT3, and EHT4, wherein the second accelerating voltages EHT2, EHT3, and EHT4 are greater than the first accelerating voltage EHT1. In the example shown, four images of the mask 100 similar to the image 110 are generated using the electron beam 202 in step S2. In this case, for example, the first image (not shown) is recorded at the accelerating voltage EHT1, that is, the first image (not shown) is recorded at the same accelerating voltage EHT1 as the accelerating voltage EHT1 used to repair the defect D in step S1. Furthermore, for example, the second image (not shown) is recorded with the acceleration voltage EHT2, the third image (not shown) is recorded with the acceleration voltage EHT3, and the fourth image 110 (FIG. 4) is recorded with the acceleration voltage EHT4.

By generating a plurality of images of the reticle 100 similar to the image 110 in FIG. 4 using different accelerating voltages EHT1 to EHT4, depth information about the coating 104 and the structure 106 formed by the coating 104 can be obtained, as shown in FIG. 6. Specifically, the depth T is perpendicular to the main extension plane of the reticle 100, wherein the main extension plane of the reticle 100 is located in the XY plane (FIG. 4). For example, an erroneous depression 116 in the sidewall 114 of the structure 106 located at the depth T2 can be detected by applying the accelerating voltage EHT2 (FIG. 6). In addition, for example, an erroneous protrusion 118 of the structure 106 located at the depth T4 can be detected by applying the accelerating voltage EHT4.

In a third step S3 of the method, reference data R of at least one second accelerating voltage EHT2, EHT3, EHT4 is generated so as to compare at least one generated image 110 of the mask 100 with the reference data R. In the example shown, reference data R is generated for each of the accelerating voltages EHT1, EHT2, EHT3, EHT4. For example, the reference data R includes a reference image, a reference size (150 to 156 in FIG. 6 ) and a reference intensity distribution (170 to 174 in FIG. 8 ).

For example, a simulation may be performed based on a known model (not shown) of the reticle 100 (i.e., a template used to manufacture the reticle 100) to generate reference data R. During the simulation, a reference image based on a simulated interaction of the electron beam is generated for each of the accelerating voltages EHT1, EHT2, EHT3, EHT4 and the known model of the reticle 100. For example, EHT3, EHT4.

For example, if a region 136 outside the defect D is captured in the generated image 110 of the reticle 100, reference data R can also be generated from the actually recorded image of the reticle 100 (e.g., image 110). Then, the reference data R can be generated based on the image analysis of the region 136. For example, the region 126 of the generated image 110 includes a plurality of periodic strip-shaped structures 106, 106', wherein the defect D exists only between two strip-shaped structures 106 (FIG. 1). Therefore, the other structure 106' can be used as a reference structure.

In the fourth step S4 of the method, the quality of the repaired defect D is determined using image analysis of at least one generated image 110 of the mask 100 and/or comparison of at least one generated image 110 of the mask 100 with reference data R of at least one second accelerating voltage EHT2, EHT3, EHT4.

In the example shown, the quality of the repaired defect D is determined by image analysis of each of four images (e.g., image 110) of the reticle 100 generated based on accelerating voltages EHT1, EHT2, EHT3, and EHT4. In this case, a comparison is made between each of the four generated images or parameters derived therefrom and the corresponding reference data R of the accelerating voltages EHT1, EHT2, EHT3, and EHT4.

In a first embodiment of the fourth step S4, in the generated image of the mask 100, for example in the image 110, the contours 138 of one or more structures 106, 106' are determined. Fig. 4 shows such contours 138 of coated structures 106, 106'. In contrast to Fig. 4, structures 106, 106', for example of the order of a few nm to a few hundred nm, are usually (very) blurry in the real image 110. By determining the contours 138, for example fitting lines to the blurry boundaries of the structures 106, 106', the contours and/or boundaries of the structures 106, 106' can be better identified.

In a first embodiment of step S4, the dimensions 140 to 146 ( FIG. 6 ) of the structure 106 are then measured based on the determined outline 138. For example, the structure width 140 is measured in the image generated for the accelerating voltage EHT1, the structure width 142 is measured in the image generated for the accelerating voltage EHT2, the structure width 144 is measured in the image generated for the accelerating voltage EHT3, and the structure width 146 is measured in the image 110 generated for the accelerating voltage EHT4. Thus, the structure widths 140 to 146 of the structure 106 are determined for different depths T1 to T4 of the structure 106.

In the example shown, the dimension is the structure width 140-146 of the structure 106. In other examples, in addition to or instead of the structure width 140-146, the dimension may also include the distance A between two structures 106, as shown in FIG. 5 .

Furthermore, for each of the accelerating voltages EHT1 to EHT4, a reference profile 148 (FIG. 4) and reference sizes 150 to 156 (FIG. 6) are determined in the reference data R generated in step S3.

The dimensions 140 to 146 of the structure 106 are then compared to the reference dimensions 150 to 156, respectively, as shown in FIG7. Specifically, the deviations of the dimensions 140 to 146 of the structure 106 from the corresponding reference dimensions 150 to 156 are determined for each of the four accelerating voltages EHT1 to EHT4. (As an example, the deviation 158 at the accelerating voltage EHT2 in FIG7 has a reference number).

The quality level of the repaired defect D is determined based on the measured deviation 158 ( FIG. 7 ), such as the size G of the corresponding deviation 158. For example, the smaller the size G of the deviation 158, the higher the quality level.

Instead of or in addition to the reference dimensions 150 to 156, which are shown in the figures and measured directly in a generated image of the structure 106' (for example, in the image 110 in FIG. 4), the structure 106' is not damaged by the defect D, the reference dimensions can also be measured in a simulated image based on a known model of the mask 100.

In the second embodiment of the fourth step S4, the intensity distribution 160, 162, 164 (FIG. 8) of each generated image (e.g., image 110) of the mask 100, that is, each accelerating voltage EHT1 to EHT4 is determined in determining the quality of repairing the defect D. The top of FIG8 shows the corresponding intensity distributions 160, 162, 164 of the accelerating voltages EHT2, EHT3, and EHT4 by way of example. Although not shown in FIG8, the intensity distribution of the accelerating voltage EHT1 can also be determined.

In the example shown, the intensity distributions 160, 162, 164 are one-dimensional intensity distributions that reflect the intensity of a corresponding image (e.g., image 110) along line 166 (FIG. 8). The center of FIG. 8 shows a detail of the reticle 100 in an image (e.g., image 110) having a coating 104, i.e., a structure 106 surrounded by a substrate 102. In addition, the line 166 along which the intensity is determined is shown. In other examples, a two-dimensional intensity distribution may also be determined.

In the region of the contour 138 of the structure 106, the intensity distributions 160, 162, 164 each have a maximum. FIG. 8 also shows a deviation 168 of the intensity distributions 160, 162, 164.

In addition, reference intensity distributions 170, 172, 174 are determined for each of the accelerating voltages EHT2 to EHT4 (or EHT1 to EHT4) in the reference data R generated in step S3. Then, deviations 168 of the generated intensity distributions 160 to 164 from the reference intensity distributions 170 to 174 of the reference data R are determined accordingly. As an example, FIG. 9 shows the deviation 168 of the intensity distribution 164 of the accelerating voltage EHT4 from the reference intensity distribution 174.

For different depths T1 to T4, by determining intensity distributions 160 to 164 for various accelerating voltages EHT2 to EHT4 (or EHT1 to EHT4) and correspondingly determining deviations of these intensity distributions 160 to 164 relative to reference intensity distributions 170 to 174 for different accelerating voltages, depth information about the structure 106 is obtained ( FIG. 6 ).

The size H ( FIG. 9 ) of the corresponding deviation 168 may be determined. Based on the determined deviation 168, such as the size H, the quality level of the repaired defect D is determined. For example, the smaller the size H of the deviation 168, the higher the quality level.

FIG10 shows graphs 176, 178, 180 that represent the magnitude H of the deviation 168 as a function of the position along the line 166 (FIG. 8, center). Specifically, graph 176 depicts the magnitude H of the deviation 168 of the intensity distribution 164 from the reference intensity distribution 174 (i.e., for accelerating voltage EHT4) as a function of the position along the line 166. In addition, graph 178 depicts the magnitude H of the deviation 168 of the intensity distribution 162 from the reference intensity distribution 172 (i.e., for accelerating voltage EHT3) as a function of the position along the line 166. In addition, graph 180 depicts the magnitude H of the deviation 168 of the intensity distribution 160 from the reference intensity distribution 170 (i.e., for accelerating voltage EHT2) as a function of the position along the line 166.

The first and second embodiments of step S4 may also be combined with each other such that dimensions 140 to 146 of structure 106 may be measured and compared to reference dimensions 150 to 156, and intensity distributions 160 to 164 may be determined and compared to reference intensity distributions 170 to 174 in an image (e.g., image 110 in FIG. 4 ).

When determining the quality of the repaired defect D, the degree of deviation between the parameters determined from at least one generated image 110 of the photomask 100 (e.g., the profile 138, the dimensions 140 to 146, the intensity distribution 160 to 164) and the reference parameters determined from the reference data (e.g., the reference profile 148, the reference dimensions 150 to 156, the reference intensity distribution 170 to 174) can be determined.

In the fifth step S5 of the method, it is determined whether the determined deviation is less than a predetermined threshold. Then, the output device 242 (HMI unit) can be controlled to output a communication: "satisfactory" and/or if the determined deviation is less than the predetermined threshold, the mask output unit can be controlled to output the repaired mask 100.

For example, the output device 242 of the apparatus 200 ( FIG. 3 ) outputs the communication: “Satisfied.” For example, the output device 242 has a human machine interface (HMI) such as a display unit and/or a speaker for outputting the communication.

The repaired reticle 100 is output and/or exhausted from the vacuum housing 204 of the apparatus 200 through, for example, a reticle output unit (not shown) of the apparatus 200 .

In the sixth step S6 of the method, if the determined deviation is greater than or equal to the predetermined threshold, the HMI unit 242 is controlled to output the message: "Unsatisfactory".

For example, the output device 242 of the apparatus 200 (FIG. 3) also outputs the communication: "unsatisfied".

In step S6 , the photomask 100 is specifically not exported and/or exhausted from the vacuum enclosure 204 of the apparatus 200 , but remains in the vacuum enclosure 204 for further inspection and/or for post-processing.

Advantageously, the repair quality level of the defect D can therefore be determined before the reticle 100 is ejected from the apparatus 200 (eg, from the vacuum enclosure 204 ).

Although the present invention has been described with reference to exemplary embodiments, the present invention can be modified in various ways.

100: mask 102: substrate 104: coating 106: structure 106': structure 108: image 110: image 112: repair shape 114: wall 116: recess 118: protrusion 120: residual material 122: fillet 124: undercut 126: area 128: volume 130: volume 132: volume 134: volume 136: area 138: profile 140: size 142: size 144: size 146: size 148: reference profile 150: reference size 152: reference size 154: reference size 156: reference dimensions 158: deviation 160: intensity distribution 162: intensity distribution 164: intensity distribution 166: line 168: deviation 170: reference intensity distribution 172: reference intensity distribution 174: reference intensity distribution 176: curve graph 178: curve graph 180: curve graph 200: equipment 202: electron beam 204: vacuum housing 206: vacuum pump 208: sample stage 210: electron column 212: electron source 214: cathode 216: anode 218: voltage source 220: channel opening 222: electron or beam optics 224: scanning unit 226: detector 228: gas supply unit 230: valve 232: gas pipeline 234: computer equipment 236: control device 238: generating device 240: judging device 242: output device 244: vacuum environment A: distance B1: structure size B2: structure size D: defect EHT1: accelerating voltage EHT2: accelerating voltage EHT3: accelerating voltage EHT4: accelerating voltage G: size H: size R: reference data T: depth T1: depth T2: depth T3: depth T4: depth X: direction Y: direction Z: direction

Further advantageous structures and aspects of the present invention are the subject of the dependent claims and the subject of the exemplary embodiments of the present invention to be described below. The present invention is explained in detail based on preferred embodiments with reference to the accompanying drawings.

FIG. 1 schematically illustrates details of a lithography mask having defects in a structured coating according to one embodiment;

FIG2 shows a cross-sectional view of the photomask along line II-II in FIG1;

FIG. 3 shows an apparatus for electron beam induction treatment of defects of the lithography mask of FIG. 1 according to one embodiment;

FIG4 shows a view similar to FIG1 , wherein the defect has been repaired using the apparatus of FIG3 ;

FIG5 shows a cross-sectional view of the photomask along line V-V in FIG4 ;

FIG. 6 shows a view similar to FIG. 5 , showing the dimensions of the repaired structured coating;

FIG. 7 shows the deviation of the dimensions of FIG. 6 compared to the reference dimensions;

FIG8 shows the one-dimensional intensity distribution of the reticle image of FIG4 (top) compared to a reference intensity distribution (bottom);

FIG9 shows details of a comparison of one of the intensity distributions of FIG8 with a reference intensity distribution;

FIG. 10 is a graph showing deviations of the intensity distribution from the reference intensity distribution of FIG. 8 ; and

FIG. 11 is a flow chart illustrating a method for performing electron beam induction processing on defects from the photomask of FIGS. 1 and 4 according to an embodiment.

100: Photomask

102: Substrate

104: Coating

106’:Structure

128: Volume

130: Volume

132: Volume

134: Volume

140:Size

142:Size

144:Size

146:Size

150: Reference size

152: Reference size

154: Reference size

156: Reference size

202:Electron beam

EHT1: Acceleration voltage

EHT2: Acceleration voltage

EHT3: Acceleration voltage

EHT4: Acceleration voltage

R: Reference data

T: Depth

T1: Depth

T2: Depth

T3: Depth

T4: Depth

Claims (15)

A method for electron beam induction treatment of a defect (D) of a lithography mask (100), comprising the following steps: a) providing (S1) an activating electron beam (202) at a first accelerating voltage (EHT1) and a treatment gas in a region (112) of the defect (D) of the mask (100) to repair the defect (D), and b) in order to determine the quality of the repaired defect (D), generating (S2) at least one image (110) of the mask (100) by providing an electron beam (202) at at least one second accelerating voltage (EHT2, EHT3, EHT4) different from the first accelerating voltage (EHT1), wherein the region (112) of the defect (D) is at least partially captured, In order to obtain depth information related to a structure (106) of the mask (100), the electron beam (202) is used under a plurality of corresponding second accelerating voltages (EHT2, EHT3, EHT4) to generate a plurality of images (110) of the mask (100), wherein the second accelerating voltages (EHT2, EHT3, EHT4) are different from the first accelerating voltage (EHT1) and the second accelerating voltages (EHT2, EHT3, EHT4) are also different from each other. The method of claim 1, wherein the at least one second accelerating voltage (EHT2, EHT3, EHT4) is greater than the first accelerating voltage (EHT1). The method of claim 1 or 2, wherein step b) is performed on-site relative to step a). A method as described in any one of claims 1 to 3, wherein steps a) and b) are performed in a vacuum environment (244), and the mask (100) is maintained in the vacuum environment (244) between steps a) and b). A method as described in any one of claims 1 to 4, wherein steps a) and b) are performed using the same scanning electron microscope device (200), and/or the electron beam (202) at the first accelerating voltage (EHT1) and the electron beam (202) at the at least one second accelerating voltage (EHT2, EHT3, EHT4) are generated by the same electron source (212). A method as claimed in any one of claims 1 to 5, comprising the following steps: Using an image analysis of the at least one image (110) generated by the mask (100) and/or a comparison based on the at least one image (110) generated by the mask (100) and a reference data (R) for the at least one second accelerating voltage (EHT2, EHT3, EHT4) to determine (S4) the quality of the defect (D) repaired. The method as claimed in claim 6, comprising the following steps: Using a simulation based on a known model of the mask (100) to generate (S3) the reference data (R), wherein, during the simulation, at least one reference image is generated based on a simulated interaction between the electron beam (202) and the known model of the mask (100), the electron beam corresponding to the at least one second accelerating voltage (EHT2, EHT3, EHT4). A method as claimed in claim 6 or 7, wherein a region (136) outside the defect (D) is captured in the at least one image generated of the mask (100), and the method comprises the following steps: Generating (S3) the reference data (R) based on an image analysis of the region (136) outside the defect (D). A method as described in any one of claims 1 to 8, wherein the determination (S4) of the quality of the repaired defect (D) comprises: Determining a contour (138) of one or more structures (106) in the at least one image (110) generated by the mask (100), and/or Determining a size (140, 142, 144, 146) of the one or more structures (106) based on the determined contour (138). A method as described in claim 9, wherein, during the determination (S4) of the quality of the repaired defect (D), a deviation between the determined profile (138) and a reference profile in the reference data (R) is determined, and/or a deviation (158) between the determined dimension (140, 142, 144, 146) and a reference dimension (150, 152, 154, 156) in the reference data (R) is determined. A method as described in claim 10, wherein the deviation of the determined profile (138) from the reference profile in the reference data (R) and/or the deviation (158) of the determined size (140, 142, 144, 146) from the reference size (150, 152, 154, 156) in the reference data (R) is determined for each of the at least one second accelerating voltage (EHT2, EHT3, EHT4). A method as described in any one of claims 1 to 11, wherein, during the determination (S4) of the quality of the defect (D) having been repaired, an intensity distribution (160, 162, 164) of the at least one image (110) generated by the mask (100) is determined, and a deviation (168) between the determined intensity distribution (160, 162, 164) and a reference intensity distribution (170, 172, 174) of reference data (R) is determined, in particular for each of the at least one second accelerating voltage (EHT2, EHT3, EHT4). A method as described in claim 12, wherein the deviation (168) of the determined intensity distribution (160, 162, 164) from the reference intensity distribution (170, 172, 174) is determined for a region (126) of the generated image (110) that includes a contour (138) of one or more structures (108) of the mask (100). A method as described in claim 12 or 13, wherein the intensity distribution (160, 162, 164) determined is a one-dimensional or two-dimensional intensity distribution. A method as described in any one of claims 1 to 14, wherein: During the determination of the quality of the repaired defect (D), a degree of deviation between a parameter determined based on the at least one image generated by the mask (100) and a reference parameter determined based on reference data is determined, and The method comprises the following steps: Determining whether the determined deviation is less than a predetermined threshold, and/or If the determined deviation is less than the predetermined threshold, controlling (S5) an HMI unit (242) to output a communication: "satisfactory", and/or controlling a mask output unit to output the repaired mask (100), and/or If the determined deviation is greater than or equal to the predetermined threshold, controlling (S6) the HMI unit (242) to output a communication: "unsatisfactory".

Images